Most ultra runners sabotage their race before the starting gun by following outdated carbohydrate loading protocols designed for marathoners. Ultra marathon carbohydrate loading requires a fundamentally different approach because your race lasts 6-30+ hours, not 2-4 hours. This 7-day protocol maximizes your glycogen stores while training your gut for the demands ahead.
Why Traditional Carb Loading Fails for Ultra Runners
Standard marathon carb loading focuses on a 3-day glycogen supercompensation window. But ultra marathons demand sustained energy over dramatically longer timeframes, requiring both maximum glycogen storage and gastrointestinal adaptation to high-carb intake during exercise.
The biggest mistake? Waiting until three days before your race to increase carbohydrate intake. Your body needs a full week to optimize glycogen storage, adapt digestive enzymes, and prevent the bloating and GI distress that plague underprepared runners.
The Glycogen Storage Difference
Research shows trained endurance athletes can store 15-20% more glycogen with a proper 7-day protocol compared to the traditional 3-day approach. For a 100-mile race, this translates to an extra 30-45 minutes of glycogen-fueled running before hitting the metabolic wall.
The 7-Day Ultra Marathon Carbohydrate Loading Protocol
Days 7-5 Before Race: Foundation Phase
Carbohydrate target: 5-7g per kg bodyweight Training: Maintain normal taper volume Focus: Quality carb sources (oatmeal, rice, sweet potatoes)
Begin slightly elevating carbohydrate intake while maintaining moderate training. This prevents the glycogen depletion phase used in old-school protocols, which research has proven unnecessary and counterproductive for ultra distance events.
Days 4-2 Before Race: Loading Phase
Carbohydrate target: 8-10g per kg bodyweight Training: Easy 30-60 minute sessions only Focus: Easily digestible carbs, reduce fiber and fat
This is your primary loading window. A 70kg (154lb) runner should consume 560-700g of carbohydrates daily. Distribute intake across 5-6 meals to minimize GI stress and optimize absorption.
Sample Day 4 Menu (70kg runner)
- Breakfast: Large bowl oatmeal with banana and honey (80g carbs)
- Mid-morning: Bagel with jam (60g carbs)
- Lunch: White rice with grilled chicken and vegetables (90g carbs)
- Afternoon: Sports drink and rice cakes (50g carbs)
- Dinner: Pasta with marinara sauce (120g carbs)
- Evening: Smoothie with fruit and dates (70g carbs)
Total: 470g carbs (add sports drinks throughout day to reach 560-700g target)
Day 1 Before Race: Maintenance Phase
Carbohydrate target: 6-8g per kg bodyweight Training: Complete rest or 20-minute shake-out Focus: Familiar foods, avoid experimentation
Slightly reduce total carbohydrate intake to prevent excessive bloating and bathroom urgency on race morning. Emphasize simple carbs (white rice, white bread, pasta) and minimize fiber, fat, and protein.
Key Takeaways
- Start carbohydrate loading 7 days before your ultra marathon, not 3 days
- Gradually increase to 8-10g carbs per kg bodyweight during days 4-2 before race
- Prioritize easily digestible carbohydrate sources and reduce fiber/fat during peak loading
- Use this protocol to train your gut for race-day fueling, not just maximize glycogen
- A 70kg runner should consume 560-700g carbohydrates daily during peak loading phase
Race Week Fueling: Your Performance Insurance Policy
Ultra marathon carbohydrate loading is your first line of defense against bonking and catastrophic energy depletion. While you’ll still need to fuel during your race, starting with maximized glycogen stores provides a critical buffer during the inevitable periods when your stomach can’t tolerate intake or aid stations are spaced far apart.
Remember: this protocol works only if you’ve practiced it during training. Run your dress rehearsal long run using the Days 4-2 protocol to ensure your gut tolerates the increased carbohydrate load without distress.
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